This invention relates to a machinist's clamp for holding metal workpieces during shaping, as by milling, drilling or the like. Such workpieces must be firmly affixed to machine tools having work surfaces with "T" slots therein. Various clamping devices are known for this purpose. More particularly, this invention relates to a clamping device for such workpieces which remains rigidly attached during loading and unloading various workpieces. The invention provides a clamp means which can greatly save setup time when clamping new workpieces resulting in greatly increased efficiency of operation.
Clamping devices for holding metal workpieces during shaping are known, as shown in FIGS. 6 and 7. Therein, step clamp 16 is shown in conjunction with step block 32 held together by bolt 42 and nut 56. Spring mechanism 54 is said to hold the clamp 16 and block 32 together when the nut 54 is loosened, as shown, and the workpiece 50 is removed. These prior art clamping devices are not entirely satisfactory in that the clamp often disengages from the block anyway, and re-setup is delayed. If the new workpiece has a significantly different height from the old and the clamps disengage as they are being adjusted, rather than saving time in re-setup, such device may actually result in an increased time required for re-setup.
The present invention overcomes the aforesaid disadvantages of the prior, known clamps. In addition, an improved step block holder, for use with "T"-slotted machine tables is provided. Also, a plate of a soft metal or plastic affixed to the clamping end of the step clamp is contemplated for use in clamping relatively soft metal workpieces.